补全对话。

A: Hi, Sam! Come here, Let’s    1    basketball.

B:     2    , I can’t.

A: What are you    3    now?

B: I am    4     my homework. Go and    5    David.

A: Thank you.     6     is he?

B: He is     7     home.

A: Is David in?

C: Yes, come    8     , please.

A: David,    9    you like to go and play basketball    10    us?

C: Certainly! Please sit here. Just a minute. Let’s go.

有关H₂O的叙述正确的是

A．H₂O的摩尔质量是18 g

B．1 mol H₂O中含有约1.806×10²³个原子

C．H₂O的物质的量是指H₂O的质量

D．H₂O中氢原子与氧原子的物质的量之比为2:1